1. Field of the Invention
The general inventive concept relates to an organic light emitting display, and more particularly, to an organic light emitting display that prevents the display quality of horizontal line shaped spot generated due to the effects of a critical dimension (CD) distribution from being degraded.
2. Description of the Related Art
Recently, flat panel displays (FPD), which solve weight and volume disadvantages of the cathode ray tube (CRT), and have the advantages of being compact and lightweight, have been spotlighted. Among flat panel displays, there are liquid crystal displays (LCD), organic light emitting diode displays (OLED), field emitter displays (FED), plasma display panels (PDP), etc.
Among other advantages, the organic light emitting display has advantages in that it has a wider use temperature range and is stronger against impact or vibration when compared to other flat panel displays. It also has a wide viewing angle and a rapid response speed which enable it to provide a clean moving image, and it has therefore been spotlighted as a next generation flat panel display.
The organic light emitting display is a display using the phenomenon that when an electron and a hole injected into a thin film of an organic material through an anode and a cathode are recombined, they form an exciton, and light having a specific wavelength is generated from the exciton. The organic light emitting display as described above is constituted using self-light emitting elements, so that it does not require a separate light source in contrast to a liquid crystal display. The brightness of the organic light emitting elements that constitute the organic light emitting display are controlled by the amount of current flowing in the organic light emitting elements.
Therefore, since the brightness of the organic light emitting display is controlled by the amount of current flowing in the organic light emitting elements, a more precise deposition process should be performed when forming the respective pixels.
The respective pixels of the organic light emitting display are made by including various constituents such as a transistor, a capacitor, etc., wherein they are formed through a deposition process using a shadow mask or a fine metal mask (FMM).
In this case, the capacity of the capacitor for each pixel may be different due to the critical dimension distribution which is generated as a result of the deposition process using the mask.
For example, in the case of a capacitor formed on the scan line for each pixel region, a problem arises in that a horizontal line shaped spot is generated according to the CD distribution generated in forming the electrode of the capacitor.
In order to reduce the effects of the CD distribution, there is a method to lower the tolerance of the mask, that is, to manufacture the mask more precisely, but this method is disadvantageous in view of considerably higher manufacturing costs.